NotepadPlusPlus

Online HTML Viewer & Previewer

View and preview HTML safely in your browser instantly. No uploads, fully offline.

Preview will render here. Scripts are disabled for security.

HTML Viewer & Previewer

What Is It?

The HTML Viewer lets you paste raw HTML markup and instantly preview how it renders in a browser-safe sandboxed iframe. It’s the fastest way to prototype, test, or inspect a snippet of HTML without spinning up a local server or browser DevTools.

How to Use

  1. Paste your HTML markup into the input panel.
  2. The rendered preview updates automatically (or click Preview to refresh manually).
  3. Use the preview panel to visually inspect layout, styling, and structure.
  4. Edit the input and see changes reflected in real time.

Example

Input:

<!DOCTYPE html>
<html>
  <body>
    <h1 style="color: #3b82f6;">Hello, World!</h1>
    <p>This renders inside a secure sandbox.</p>
  </body>
</html>

Output: A live preview showing a blue heading “Hello, World!” followed by the paragraph.

Benefits

  • Instant visual feedback — no need to create a local file and open it in a browser.
  • Safe sandbox — the preview runs in a restricted iframe that cannot access parent page resources.
  • No server required — entirely client-side, works offline after load.
  • Great for snippets — ideal for email templates, component fragments, and one-off demos.

Common Use Cases

  • Previewing HTML email templates before sending.
  • Testing static markup snippets copied from StackOverflow or documentation.
  • Quickly checking how a specific HTML structure renders across styling contexts.
  • Verifying widget embed codes (forms, banners, badges) before placing them on a live site.
  • Prototyping small UI components without setting up a project.

Frequently Asked Questions

Is JavaScript inside the HTML executed in the preview?

For safety, JavaScript execution within the sandboxed preview is restricted. HTML structure and CSS styling will render correctly, but scripts may be blocked depending on browser sandbox policies.

Can I paste a full HTML page including <head> tags?

Yes. Full HTML documents including <!DOCTYPE>, <head>, and <body> are supported in the preview iframe.

Does the viewer support external stylesheets or fonts?

External resources (CDN stylesheets, Google Fonts, etc.) will load if you have an internet connection, since the iframe can fetch public URLs.

Is my HTML content private?

Absolutely. No part of your HTML is transmitted to any server. The viewer renders everything locally inside your browser’s sandbox.

How is this different from the Smart Editor?

The Smart Editor is a full code-editing environment for writing and saving code. The HTML Viewer is focused on fast rendering preview of a snippet without any editing overhead.